We asked: Did you ever have a client who let you know that the bank had made a mistake in his or her favor?
By Barry J. Fellner II (Bank One/Chase Bank, Columbus, Ohio)

Picture it. 1980. Minneapolis, Minnesota.
My younger brother had purchased new clothes and things. I knew he had just gotten a job at McDonalds, but did not think they paid enough for him to afford all this stuff. He was still only 17 at the time.
So I asked. "From the bank." He always was a fount of information. I drilled for details. It was not a loan. It was not his paycheck.
It seems that his "sketchy" older friend had found a "bug" in the ATM software at the local bank. Back in those days the nightly processing took down the ATM network so it could not check the balance on your account. Instead, it just granted you up to $200. But that wasn't even the bug! If you went to your own bank's ATM, they would eventually reconcile to your account, and you could end up in a negative balance situation, with all the attendant fees, etc.
If you went to some other bank, though, the system did not completely record the transaction, and the withdrawal did not appear on your account after several months, if ever.
So brother and buddy went to the bank a couple times a week to get money. Now I was only 24, but this sounded not only fishy, but I was a computer programmer and did not think this was even possible.
So I went with my brother on his next banking excursion.Sure enough, he got $200. I knew darnn well that I did not have that much in my account, so I punched in a withdrawal of $200, and instead of an error, out came the money. So I did it again. Same result.
So now I stood there holding $400 in cash, most of which was not mine. I dragged my brother down to that bank branch in the morning and explained to the manager what happened. I presented my ill gotten $400 and brother offered his $200.
Now yes, there was a dust-up, but thankfully we were forgiven because we reported and returned the money.
I do not know to this day how many others were participating in after-hours banking and how much money may have been involved. I did notice, however, changes to ATM processing followed fairly quickly.